Automatic shutter-speed control

ABSTRACT

In a camera having a photoelectric system for establishing shutter speed, means are provided for detecting the presence of a predetermined condition in the photoelectric control system and for establishing a predetermined exposure interval independently of the photoelectric control system in response to the detection of such a predetermined condition. In the preferred embodiment, the photoelectric control system includes a time-delay circuit energizable by a battery in a receptacle, and the camera includes a mechanical shutter control having a predetermined speed which is actuated in response to detection by a sensing arm of the absence of a battery in a battery receptacle.

[ 51 June 20, 1972 [54] AUTOMATIC SHUTTER-SPEED CONTROL Inventor:

[72] Wolfgang Ort, Stuttgart-Bad Cannstatt,

Germany Assignee: Eastman Kodak Company, Rochester,

June 8, 1970 [30] Foreign Application Priority Data June 6, 1969 Germany..P 19 28 877.8

Field ofSearch ..95/10 C, 10 CE, 10 CT, 53 R, 95/53 E, 53 EB [56]References Cited UNITED STATES PATENTS 3,326,103 6/1967 Topaz ..95/l0 CTPrimary Examiner-Joseph F. Peters, Jr. Attorney-Robert W. Hampton andWilliam F. Delaney, Jr.

57 ABSTRACT In a camera having a photoelectric system for establishingshutter speed, means are provided for detecting the presence of apredetermined condition in the photoelectric control system and forestablishing a predetermined exposure interval independently of thephotoelectric control system in response to the detection of such apredetermined condition. In the preferred embodiment, the photoelectriccontrol system includes a time-delay circuit energizable by a battery ina receptacle, and the camera includes a mechanical shutter controlhaving a predetermined speed which is actuated in response to detectionby a sensing arm of the absence of a battery in a battery receptacle.

5 Claims, 1 Drawing Figure AUTOMATIC SHUTTER-SPEED CONTROL BACKGROUND OFTHE INVENTION This invention relates to exposure controls for use in aphotographic apparatus, such as cameras, and more particularly to ashutter control system including a photoelectric circuit forestablishing shutter speed automatically in accordance with the level ofscene illumination.

There are numerous prior art exposure control systems for establishingshutter speed as a function of the level of scene illumination.Originally such devices were of the programmed shutter type in which ashutter mechanism was adjusted prior to an exposure in accordance withthe level of scene light immediately prior to the exposure. Morerecently, however, exposure control devices have been provided whichinclude a photoelectric time-delay circuit that integrates scene lightduring an exposure interval to terminate the exposure interval a periodof time after its initiation as a function of scene illumination.Typically the timing circuit in such exposure control devices isactuated in synchronization with the opening of the shutter, and thecircuit then actuates the shutter mechanism to close the shutter aperiod of time thereafter in accordance with the level of sceneillumination received during the exposure interval. Such devices usuallyinclude an electromagnetic transducer that actuates the shuttermechanism to close the shutter in response to a signal from a triggercircuit associated with an integrating circuit comprising a photocell inseries with an integrating capacitor. The capacitor is charged throughthe photocell at a rate determined by the resistance value of thephotocell until the voltage across the capacitor reaches a predeterminedvalue at which the trigger circuit is actuated to energize or deenergizea solenoid to actuate the shutter mechanism to terminate the exposureinterval.

Of course, such shutter control circuits usually are energized by one ormore batteries which are accommodated in a receptacle in the camera. Insuch cameras the condition of the battery is critical to thesatisfactory operation of the electrically timed shutter, and thereforesuch cameras often are provided with a battery tester that provides anindication to a camera operator of the condition of the battery, such asfor example described in German DAS 1,284,278 (57a-32/05). However, whenthe battery is not in operating condition, the camera usually isrendered inoperative until it is provided with an operative battery.Such arrangements reduce the utility of the camera, since instances mayoccur in which an operative battery is not immediately or readilyavailable.

SUMMARY OF THE INVENTION It is an object of this invention to provide acamera having a photoelectric shutter-control system with means forautomatically establishing a predetermined shutter speed independentlyof the photoelectric system in response to a sensed condition within thephotoelectric system.

It is another of this invention to provide such an independent controlin such a camera that establishes a predetermined shutter speed when thephotoelectric shutter-control system is rendered inoperative.

It is a further object of this invention to provide a camera having aphotoelectric shutter-control system energizable by a battery in areceptacle in the camera with mechanical shutter control forestablishing a predetermined speed when there is no battery in thereceptacle.

These objects are accomplished according to the present invention in acamera having a photoelectric shutter-control circuit by an independentcontrol apparatus comprising means actuatable for establishing apredetermined shutter speed independently of the photoelectric shuttercontrol system, means for sensing a predetermined condition within thecontrol system and means associated with the sensing means for actuatingthe independent shutter-speed control when the sensor detects thepredetermined condition. Preferably, the sensing means is adapted todetect whether the photoelectric shutter-control system is energized, sothat the independent control system is actuated when the photoelectricsystem is not energized.

In the preferred embodiment of the invention, the photoelectricshutter-control system includes a battery energizable time-delay circuitwhich establishes the length of an exposure interval as a function ofthe level of scene illumination, and the independent control apparatusis adapted to be actuated in response to detection that thephotoelectric control system is not energized by a battery. Preferably,the sensing means comprises a sensing member extending into a batteryreceptacle in the camera, and the member is associated with means foractuating the independent shutter control when there is no battery inthe receptacle.

In the preferred embodiment such an apparatus comprises a couplingmember having an arm extending into the battery receptacle and disposedfor movement from an inoperative position in which it engages a batteryin the receptacle to an operative position when no battery is in thereceptacle in which it is actuatable by a shutter opening mechanism toactuate a shutter closing mechanism to terminate an exposure intervalafter a predetermined time. Thus, when the photoelectric shutter controlsystem is rendered ineffective due to insufficient battery power, thecamera operator can remove the battery from the camera to automaticallyactuate the independent control to mechanically establish apredetermined shutter speed. The mechanically established shutter speedis determined by the inherent speed of the shutter mechanism, which canbe adapted to provide any desired speed, such as for example 1/60 sec.,at which the camera is adapted for use with a flash unit.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows an elevated view of afocal plane shutter mechanism having an independent shutter-speedcontrol according to the preferred embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION Although this invention can beemployed with several different types of presently known shuttersystems, the preferred embodiment of the invention, as described herein,is employed in a camera 1 of the type having a focal plane shutterincluding an opening shutter mechanism 2 and a closing shutter mechanism3, which control the movement of a leading shutter curtain 4 and atrailing shutter curtain 5, respectively. Only a portion of each ofthese shutter curtains is shown to indicate their relationship with therespective shutter mechanisms. The focal plane or film plane is notshown, and the portions of the shutter curtain extending across the filmplane is not shown, since such arrangements are well known. The openingand closing shutter mechanisms each include a rotatable plate 6 and 7,respectively, which are biased by springs (not shown) in a clockwisedirection as indicated by the arrows A and B, respectively. The shuttercurtains are attached to their respective rotatable plates by screws 8and 9 in arcuate recesses 10 and 11, respectively. As shown in thedrawing, the shutter is in its tensioned or cocked" condition with therotatable plate of the open shutter mechanism retained against itsspring bias by a retaining latch 12 rotatably mounted on a pivot pin 13and biased by a spring 14 into engagement with a notch 15 in the plate6, and with the rotatable plate 7 of the closed" shutter mechanismretained by a latch 16 rotatably mounted on a pivot pin 17 and biased bya spring 18 into engagement with a notch 19 in the plate 7. The plates 6and 7 are moved to this tensioned position by a cocking lever 20 whichis rotatable counterclockwise about a pivot 21 in the direction of arrowC against the bias of a spring 22 to move the plates to the positionsshown by engagement with pins 23 and 24 on plates 6 and 7 respectively.The cocking lever 20 is retained in this tensioned position byengagement with a release member 25 which is actuatable from theexterior of the camera by an operator to release the cocking lever forrotation in a clockwise direction as indicated by the arrow C under theinfluence of the spring 22.

The latch 16 is associated with an armature 26 positioned adjacent anelectromagnetic coil 27 so that energization of the coil will attractthe armature 26 to rotate latch 16 counterclockwise against the bias ofthe spring 18 out of retaining engagement with the rotatable plate 7 ofthe closed" shutter mechanism.

The electromagnetic coil 27 is electrically connected with an electronictime-delay circuit, indicated by block 30, which is energizable by abattery 32 and is adapted to energize the coil a period of time afterthe circuit is actuated by the closing of a control switch 34, whichperiod of time is established by the control circuit as a function ofthe level of illumination incident on a photoelectric member 36. Theswitch 34 can be associated with the shutter opening mechanism in anydesired manner, such that the switch 34 is automatically closed toactuate the time-delay circuit 30 simultaneously with the initiation ofan exposure interval. There are numerous time-delay circuits in theprior art which can be employed in this shutter control system, so thatfurther description of the circuit is not considered necessary.

The above-described shutter system operates under the control of thephotoelectric control system in the following manner. When an operatoractuates the release lever 25, it is disengaged from the cocking lever20 to permit the cocking lever to rotate in a clockwise direction asindicated by arrow D out of engagement with the pins 23 and 24 until itengages a detent 36 on the latch 12 to disengage the latch from theplate 6, immediately prior to engagement with a stop member 37. Theplate 6 is free to rotate in the direction A to cause the leadingshutter curtain 4 to travel across the film plane and initiate anexposure interval. At the same time the switch 34 is closed in responseto actuation of the shutter opening mechanism to actuate the time-delaycircuit 30 which subsequently energizes the electromagnet 27 after aperiod of time established as a function of the level of illuminationincident on the photocell 36. When the electromagnet is energized itattracts the armature 26 to disengage the latch 16 from the rotatableplate 7 of the shutter closing mechanism. Thus, the shutter closingmechanism is caused to terminate the exposure interval in response toenergization of the electromagnet 22, so that the exposure interval isdetermined by the timing circuit 30. However, if the battery 32energizing the circuit 30is not in operative condition, theelectromagnet 27 would not be energized to terminate the exposureinterval, and the shutter would remain open indefinitely.

To avoid rendering the camera inoperative when an operative battery isnot available, a camera according to the preferred embodiment of thisinvention is provided with a mechanism for automatically actuating theshutter closing mechanism a predetermined period of time after actuationof the shutter opening mechanism when a battery receptacle 38 does notcontain a battery. This mechanism includes a coupling lever 40 pivotallyand slidably mounted on the pin 13 with an extension arm 42 that extendsinto the battery receptacle 38. When a battery is in the receptacle itis engaged by the arm 40 which is moved thereby against the bias of aspring 44 into engagement with a stop member 46, in which position anotch 48 defined by the coupling lever 40 is aligned with the path ofmovement of a detent 50 on the rotatable plate 6 so that the couplingmember is disabled. However, if no battery is in the compartment 38 thecoupling lever is moved by its spring bias into engagement with a secondstop member 52, in which position a portion 54 of the coupling member islocated in the path of the detent 50 on the rotatable plate 6.Engagement of the portion 54 with the detent 50 causes the couplinglever to slide on its mount 13 in the direction of the arrow C inresponse to actuation of the shutter opening mechanism to initiate anexposure interval. When the coupling lever 40 moves in the direction ofarrow C, an edge portion 56 is moved into engagement with a lug 58 onthe retaining latch 16 to move the latch out of engagement with theplate 7 to thereby actuate the shutter closing mechanism to terminatethe exposure interval. Preferably the detent 58 is a rotatable eccentricto permit minor adjustments of the exposure time. Thus, when no batteryis in the compartment 38 the coupling member 40 is actuated to establisha predetermined exposure time which is a function of the inherent timelag required for the rundown operation of the shutter mechanisms.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

I Claim:

1. In a camera including an energizable photoelectric shutter-controlsystem for terminating an exposure interval a period of time afterinitiation thereof, the period of time being established by the controlsystem as a function of the level of scene illumination, the improvementcomprising:

a. actuatable means for terminating an exposure interval independentlyof the control system a predetermined time after initiation thereof;

b. means for sensing whether the control system is energized; and

c. means associated with said sensing means for actuating saidindependent terminating means when the control system is not energized.

2. In a camera including a battery-energizable, photoelectricshutter-control system for terminating an exposure interval a period oftime after initiation thereof, the period of time being established bythe control system as a function of the level of scene illumination, theimprovement comprising:

a. actuatable means for terminating an exposure interval independentlyof the control system a predetermined time after initiation thereof;

b. means for sensing whether the control system is energized by abattery; and

c. means associated with said sensing means for actuating saidindependent terminating means when the control system is not energizedby a battery.

3. In a photographic camera including a shutter mechanism for initiatingand terminating an exposure interval, a batteryoperable photoelectricshutter-control system for terminating an exposure interval a period oftime after initiation thereof, the period of time being established bythe control system as a function of the level of scene illumination, anda receptacle for receiving a battery for energizing the control system,the improvement comprising:

a. actuatable means for terminating an exposure interval independentlyof the control system a predetermined time after initiation thereof;

b. a sensing arm extending into the battery receptacle for sensing thepresence and absence of a battery therein; and

c. means associated with said sensing means for actuating saidindependent terminating means when there is no battery in the batteryreceptacle.

4. In a photographic camera including a shutter mechanism for initiatingand terminating an exposure interval, a receptacle for receiving abattery, and an electromagnetic transducer energizable by a battery inthe receptacle and actuatable to actuate the shutter mechanism toterminate an exposure interval, the improvement comprising:

a. actuatable means for terminating an exposure interval independentlyof the electromagnetic transducer a predetermined time after initiationthereof;

b. means for sensing the presence and absence of a battery in thebattery receptacle; and

c. means associated with said sensing means for actuating saidindependent terminating means when there is no battery in the batteryreceptacle.

5. In a camera including a shutter-opening mechanism for initiating anexposure interval, a shutter-closing mechanism for terminating theexposure interval, a battery-energizable photoelectric shutter-controlsystem for actuating the shutterclosing mechanism to terminate anexposure interval a period of time after initiation thereof, the periodof time being established by the control system as a function of thelevel of scene illumination, and a receptacle for receiving a batteryfor energizing the control system, the improvement comprising:

a actuatable means for actuating the shutter-closing mechanismindependently of the control system for terminating an exposure intervala predetermined time after initiation thereof;

1. In a camera including an energizable photoelectric shuttercontrolsystem for terminating an exposure interval a period of time afterinitiation thereof, the period of time being established by the controlsystem as a function of the level of scene illumination, the improvementcomprising: a. actuatable means for terminating an exposure intervalindependently of the control system a predetermined time afterinitiation thereof; b. means for sensing whether the control system isenergized; and c. means associated with said sensing means for actuatingsaid independent terminating means when the control system is notenergized.
 2. In a camera including a battery-energizable, photoelectricshutter-control system for terminating an exposure interval a period oftime after initiation thereof, the period of time being established bythe control system as a function of the level of scene illumination, theimprovement comprising: a. actuatable means for terminating an exposureinterval independently of the control system a predetermined time afterinitiation thereof; b. means for sensing whether the control system isenergized by a battery; and c. means associated with said sensing meansfor actuating said independent terminating means when the control systemis not energized by a battery.
 3. In a photographic camera including ashutter mechanism for initiating and terminating an exposure interval, abattery-operable photoelectric shutter-control system for terminating anexposure interval a period of time after initiation thereof, the periodof time being established by the control system as a function of thelevel of scene illuminatioN, and a receptacle for receiving a batteryfor energizing the control system, the improvement comprising: a.actuatable means for terminating an exposure interval independently ofthe control system a predetermined time after initiation thereof; b. asensing arm extending into the battery receptacle for sensing thepresence and absence of a battery therein; and c. means associated withsaid sensing means for actuating said independent terminating means whenthere is no battery in the battery receptacle.
 4. In a photographiccamera including a shutter mechanism for initiating and terminating anexposure interval, a receptacle for receiving a battery, and anelectromagnetic transducer energizable by a battery in the receptacleand actuatable to actuate the shutter mechanism to terminate an exposureinterval, the improvement comprising: a. actuatable means forterminating an exposure interval independently of the electromagnetictransducer a predetermined time after initiation thereof; b. means forsensing the presence and absence of a battery in the battery receptacle;and c. means associated with said sensing means for actuating saidindependent terminating means when there is no battery in the batteryreceptacle.
 5. In a camera including a shutter-opening mechanism forinitiating an exposure interval, a shutter-closing mechanism forterminating the exposure interval, a battery-energizable photoelectricshutter-control system for actuating the shutter-closing mechanism toterminate an exposure interval a period of time after initiationthereof, the period of time being established by the control system as afunction of the level of scene illumination, and a receptacle forreceiving a battery for energizing the control system, the improvementcomprising: a. actuatable means for actuating the shutter-closingmechanism independently of the control system for terminating anexposure interval a predetermined time after initiation thereof; b.means for extending into the battery receptacle sensing the presence andabsence of a battery therein; and c. means associated with said sensingmeans for actuating said independent terminating means when the sensingmeans detects the absence of a battery in the receptacle.